I have decided to move this post across from bsdforums. Thankfully, floppy disks are getting less common (and not before time!!), but some poor luser is sure to end up stuck with them.

[Instructions for FreeBSD]
The floppy device is known as /dev/fd0 for the first (and generally only) floppy drive.
The command to use to make it available is mount. mount can do a lot of things, so it's man page is complex. Read it - some other time.
To use an msdos floppy disk, do this.
1. Gain root privileges. Either log in as root, use sudo (if you have that installed) or use the su command
$ su
password: << type in the root password

2. create a folder to use to access the drive. It can be anywhere.
# mkdir /floppy